Electric discharge device



Jan. 18, 1949. J. E. BEGGS ELECTRIC DISCHARGE DEVICE Filed Maroh' 27, 194

Inventor": James EBeggs,

His Attorney.

Patented Jan. 18, 1949 2,459,487 ELECTRIC DISCHARGE DEVICE James E. Beggs, Scotia, N. Y., assignor to General Electric Company, a corporation of New York Application March 27, 1946, Serial No. 657,408

My invention relates to electric discharge devices and more particularly to improved discharge devices in which the high frequency and direct current circuits are isolated.

In my copending application Serial No. 651,234, filed March 1, 1946, now Patent No. 2,455,851, I have shown and described an electric discharge device particularly adapted for operation over a wide range of frequencies in which the control grid circuit is shielded from the anode by the cathode structure and in which the cathode and screen grid are directly bypassed with respect to high frequency currents Within the discharge device. The present invention incorporates these features and in addition provides a structure which is particularly adapted for use in radio sets as an amplifier. The structure is adapted to be supported on a chassis with the direct current connections made to the terminals thereof on one side of the chassis member and with the a new particularly adapted for operation over a wide 1 range of frequencies.

It is still another object of my invention to provide an electric discharge device structure which is particularly adapted for use in cascaded amplifier circuits.

Further objects and advantages of my invention will become apparent as the following description proceeds, reference being had to the accompanying drawing, and its scope will be pointed out in the appended claims. In the drawing, Fig. 1 is a perspective view of an electric discharge device embodying my invention; Fig. 2 is an elevational view in section of the device shown in Fig. 1; Fig 3 is a plan view of a portion of the device shown in detail the grid and cathode construction, and Fig. 4 is a schematic representation of an amplifier circuit employing the device of Figs. 1 to 3.

Referring now to the drawing} have shown my invention embodied in an electric discharge device including an envelope'constructed of tele scoping metal members I and 2 which, as illustrated, may be of substantially rectangular cross-section in one plane and when assembled provide a substantially U-shaped cross-section in Fig. 2 illustrating in more 8 Claims. (Cl. 25027.5)

2 a plane transverse to the first mentioned section. The members i' and 2 are provided with circular openings defined by inwardly directed flanges 3 and 4 which extend in generally parallel relation. The envelope of the device is completed by domelike glass insulators 5 and B which are sealed to the flanges 3 and l respectively, and which support terminals 7 and 8 at opposite ends of the device in insulated relation with respect to each other and with respect to the envelope. The terminal 8 provides an external connection for a planar anode 9 which is provided by the inner end wall of an extension of the terminal 8 and the terminal 1 provides a support and an electrical connection for the control grid H! which is supported from the terminal structure by a pair of parallel metal supports 1 I. As illustrated in Figs. 2 and 3, these supports extend on opposite sides of a cathode member I 2 and the mesh of grid it is welded or otherwise bonded to the upper ends thereof. It is apparent that some tension for holding the grid in shape under operating conditions may be provided for forcing these arms together slightly before and during the welding operation.

The cathode may be similar to the standard receiving type cathode now widely employed in radio tubes and, as illustrated, includes the tubular member 12 which may to advantage be of rectangular cross-section and coated on at least the upper side thereof in the region beneath the grid mesh, as shown at [2, with an electron emission enhancing material such as a mixture of alkaline earth oxides. The cathode member l2 is adapted to be brought to electron emission temperature by a twisted heater element l4 received within the member i2 and insulated therefrom in any suitable manner as by a coating of aluminum oxide. The cathode member I2 is thus positioned on the side of the control member opposite the anode and is supported by a pairof metal flanges i5 and it which extend in parallel and in spaced relation and are received between the flanges 3 and 4 of the envelope members I and 2. The flange I5 is spaced from the flange 3 of the envelope member by an insulating disk or washer l! which maintains the cathode insulated from the envelope with respect to direct current voltages and bypasses the cathode to the envelope with respect to high frequency voltages. In a similar "manner: a screen grid is and suppressor grid iii are positioned between the control grid and the anode and each is provided with a marginal metal supporting member 20 arranged between and in parallel relation with respect .to

the flanges 3 and 4. As illustrated, the washers 20 are mutually insulated and insulated with respect to the envelope member 2 and the cathode support I6 by insulating washers 2|. With this construction it is apparent that the suppressor grid, screen grid and cathode are all connected together and to the metal envelope with respect to high frequency voltages but are mutually insulated with respect to direct current voltages.

All of the direct current connections are adapted to be made with the various electrodes of the device through a plurality of contact prongs 22 to 21 inclusive which are sealed'through suitable openings in one side of the envelope member I by a body of glass 28 which, as best illustrated in Fig. 2, is positioned between the inner surface of one side of member I and a retaining metal member 29. As indicated, the terminal prongs 22 to 21 are connected respectively with the suppressor grid, screen grid, cath- 'od'e heater terminalsand'to the envelope member .I through a getter 30. The getter may to advantage be of "the type which is adapted to remain intact during the life of the tube so that thexconducting'portions of the tubeenvelope may rbemaintained' at direct current ground potential by the terminal prong .2].

It will .be apparent that the construction descuibed above incorporates features generic to my aboveementioned copen'ding application including'theshielding .of the control member lead- :in by the cathode structure and the direct bypass 'ofithe screen grid to the cathode within the tube. Thestrnctnreby which these features are realized .is. somewhat different. in addition, the device embodying my present invention provides for the Hawking of the direct current connections from one side of the envelope, :and for making the input and output high frequency connections from th opposite ends thereof, thereby adapting the 1711176 particularly for cascaded amplifier circuits such frequently employed in radio receiving sets.

.Jzn Fig. Fl I have illustrated schematically the application of a discharge device embodying my present: invention "to .an amplifier circuit. The device shown in Fig. 4 is diagrammatic and elements corresponding to the elements of Figs. 1 to 3: have been designated by the same reference numerals. As illustrated in Fig. 4, the input or grid-cathode circuit includes an input transformer 3%. having the primary Winding tuned'by a parallelyconnected capacitor $2 and the secondary windingtunerl- .by :aparallel connected capacitor 3.3. Cine terminal of the secondary winding is connected directly with'the grid terminal '5 and the other terminal is capacitively coupled with the envelope of the device by a capacitor including .a plate-like conductor 34 and insulator 3'4. As will :be readily appreciated, the envelope of :the device is connected with the cathode with 2: eet to. high frequency voltages as a result of the bypass capacitor provided :by the insulating washer ill and the opposed metal surfaces on cp- =posite sides thereof. The direct current connec- 'tion for the input circuit includes a resistor 35 which connected "with the negative terminal ofit'he 'grid biasor C battery. In a similar 132L11- ner, the output :circuit .is connected between the anode and cathode. As illustrated, the output transformer 36 has the primary winding thereof tuned by a capacitor .37 and the secondary windi-ng tuned @bya capacitor 38.. One terminal of the secondary winding is connected directly with the anode terminal 8 and the other terminal is connected to the input of the next stage and that the required physical spacing between successive stages is small. Also, the high frequency circuits are all located above the chassis While the direct current circuits are all positioned below the chassis, utilizing the metal chassis as an effective shield. It will be readily appreciated by those skilled in the art that the above construction is also well suited to circuits having distributed characteristics, such as concentric line circuits, and if desired the cross section of the envelope may %be made circular ililSlZiEEUd of square, which -case the concentric connections may be readily made to the opposite ends ozfthe device. 1

lVhiie I have show/nancl described a particular embodiment of my invention, it will be apparent to those skilled in the art that changes and modifications may be made without departing from the features of my inuention, and I therefore aim in the appended claims ito cover :allsuch-changes and modifications as t'fall within the true spirit and scope of my invention. I

W hat I claim .as new and desire to secure by Letters Patent :of thel'lnited States :is':

1. An electric discharge. device including an envelope, a plura ity ofielectro'deszsupported withinsaid envelope including an ."anode-a cathode, 'a control grid, :means supporting said anode from one end of :said envelope,:meamssupporting said control gr-i'd from :the other :end of said envelope, said envelope including a'metalrs'i'd'e wall insulated with respect to supports for said anode and control .gridand-conneccted withsaid'cathode with respect to :high frequency voltages, a, heater element in heat exchangerelation with said cathode, and a plurality of terminals sealed through the side wall *of said envelope and connected respec tively with the terminals of :said heater element and said cathode for supplying direct current voltages thereto.

2. An electric discharge device including an envelope comprising a pair of cup-like metal members assembled. in telescopic relation, an

anode'supported from one :end of said envelope, :2.

control member supported-from the other end of said envelope, a cathode structure including marginal portions received between opposedsurfacesof cup-likennembers and positioned on the side of said control member remote from said anoderand insulating rmeans interposed between .thEQathOGE'StFUCtHIQ :and the opposed portions of said cup-like .members insulating said cathode from. said em elone. respect to direct current voltagesiand'ccrmect ing .said cathode with said 'enveicpe with respect to high frequency voltages.

3. An electric discharge device comprising an envelope including a :of ;cup-like :metal mem- 'bers assembled in telescopic relation and provided with apertures at opp'osite ends thereof, a pair of conductors sealed respectively through the apertures in the opposite ends of said envelope, an anode'supported on one of ssaid;conductors,.:a control membersupported 'on the other-of said con ductors, and a cathode supported within said envelope on the side of said control member remote from said anode, and a plurality of terminals sealed through a side wall of said envelope and in insulated relation with respect thereto and providing direct current connections for the device.

4. An electric discharge device including an envelope having opposed metal side walls each provided with an aperture, a pair of insulators each sealed to one of said side walls and closing the aperture therein, an anode supported from one of said insulators and a control member supported from the other of said insulators, a cathode supported on the side of said control member opposite said anode and including marginal portions positioned between opposed portions of said side walls, and insulating means interposed between said marginal portions and said opposed portions insulating said cathode and said envelope with respect to direct current voltages while connecting said marginal portions and said envelope with respect to high frequency voltages.

5. An electric discharge device including an envelope having a metal side wall and metal end walls joined therewith and provided with aligned openings, an insulator sealed to said end walls closing said openings, an anode supported from one of said insulators and a control member supported from the other of said insulators, a cathode supported on the side of said control member opposite said anode and including marginal portions positioned between the end walls of said envelope, an additional control member including a marginal portion received between said end Walls, insulating means interposed between the marginal portions of said cathode, said additional control member and said end walls insulating said A cathode, said envelope and said additional control member with respect to direct current voltage while connecting said marginal portions and said envelope with respect to high frequency voltages, and a plurality of terminals sealed through said side wall.

6. An electric discharge device including an envelope having a metal side wall provided with inwardly directed flanges at opposite ends thereof and defining aligned openings in the opposite end walls of said envelope, a pair of insulators sealed respectively to said flanges, an anode supported from one of said insulators and a control member supported from the other of said insulators, a cathode supported on the side of said control member opposite said anode and including marginal portions positioned between the inwardly directed flanges of said wall envelope, insulating means interposed between said marginal portions and said flanges insulating said cathode with respect to direct current voltage while connecting marginal portions with said device with respect to high frequency voltages, and a plurality of terminals sealed through said side wall.

Z. An electric discharge device comprising a metal envelope including a pair of metal memhermetically joined together and providing opposed end walls, an anode supported in insulated relation from one of said end walls, a control member supported in insulated relation from the other of said end walls, a cathode and at least one additional electrode positioned within said envelope and having marginal portions received between opposed walls of said metal members, insulating washers received between said cathode, said additional electrode and the opposed walls of said metal members insulating said cathode, said additional electrode and said envelope with respect to direct current voltage while connecting them together and to the envelope with respect to high frequency voltages, and a plurality of terminals sealed through a side wall of said envelope connected respectively with said cathode and said additional electrode for supplyin voltages thereto independently of the high frequency circuits of the device.

8. An electric discharge device comprising a metal envelope including a pair of metal members hermetically joined together and providing opposed end walls, an anode supported in insulated relation from one of said end walls, a control ember supported in insulated relation from the other of said end walls, a cathode positioned within said envelope and having marginal portions received between the opposed walls of said metal members, insulating washers received between the marginal portions of said cathode and the opposed walls of said metal members insulating said cathode and said envelope with respect to direct current voltages while connecting them together with respect to high frequency voltages, and a plurality of terminals sealed through the side wall of said envelope.

JAMES BEGGS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,056,035 Beggs Sept. 29, 1936 2,288,380 Wing, Jr. June 30, 1942 2,391,927 Segerstrom, Jr. Jan. 1, 1946 2,413,689 Clark et a1 Jan. 7, 1947 

